switching dash clusters

I have a 1993 s-10 blazer tahoe edition. my model has a vortec engine and electronically controlled transmission(automatic 4 forward gears including overdrive). At a local yard i picked up a dash speedometer cluster from a 90-91 blazer(couldnt tell exactly what year, grill was missing. may have even been a 92) with vortec and electonic transmission(also automatic 4 forward gears with overdrive). The gauges and instrument indicators are the same except it`s speedometer goes up to 120mph instead of my current 85mph speedometer. I wanted to put the 120mph one on my car(don`t ask), but I was told there may be a difference between the gear ratio in the transmission for the cluster I have now, and the older s-10`s transmission and cluster which I just picked up.

in other words, will this semi-older cluster work with my newer car, or are the transmission`s speed sensor gear ratios for the late 80s early 90s s-1o blazers different by year?

thats a mouthfull.....

I'm pretty sure its a different tranny isn't it? There would probably be a different ratio.

The both have the same engine
(v6 4.3L vortec),and they both are automatic, 4 speed thats including overdrive. Only the year the car was producedis different. Does anyone who worked on mutiple early 90s s-10 blazers know if there were changes made to the overdrive tranys in the early 90s.